This disclosure relates to a toner-amount detection sensor.
Typical toner detection sensors used in image forming apparatuses, such as printers and multifunction peripheral, are reflective optical sensors each including a light emitter that emits light to toner on an image carrier and a light receiver that receives the reflected light (specularly reflected light and/or diffusely reflected light) to detect the amount of the toner based on the output voltage of the light receiver.
Some of such sensors have the light emitter and light receiver that are surface-mounted on a board.